Oral solid dosage forms have been described in the prior art which are based on pellets which are dispersed in a matrix which is compressed into a tablet. U.S. Pat. No. 5,637,320 describes a formulation where pellets of naproxen are coated with a multilayer membrane which controls the release of the naproxen. The present applicant has discovered that it is not necessary to provide coated pellets in a compressed tablet matrix to obtain controlled release properties of a drug contained in the pellets if the matrix is formulated to contain a swellable pharmaceutical polymer.
Typically, in the prior art, pellets have been used in formulations for sustained or controlled release where the pellets are coated with controlled or modified release polymers to obtain a sustained or controlled release dosage form. It has been discovered that uncoated drug pellets, when combined with a matrix comprising a swellable or controlled release polymer will provide extended release of the pharmaceutical compound.
A compressed tablet, made with a controlled release polymer in the matrix, which is preferably a carbomer, in combination with uncoated drug containing pellets can provide a controlled release including zero-order release formulations suitable for 8-24 hour dosing, depending on the drug and the desired frequency of dosing.